Sieve (RFC 5228) is a language for filtering e-mail messages. It is designed to be implementable on either a mail client or mail server. It is meant to be extensible, simple and independent of access protocol, mail architecture and operating system. It is suitable for running on a mail server where users may not be allowed to execute arbitrary programs, such as on black box IMAP servers, since in its basic form it has no variables, loops or ability to shell out to external programs.

Sieve.info is a wiki site that attempts to gather documents, implementations, notes, ideas and any kind of information regarding Sieve.